Replacing substrings in a string Java

Question

I'm trying to replace multiple substrings in a string, for example I have the following string wordlist

one    two    three

Where I want to replace \t tab characters with \r\n new line characters.

I define the separator variable as \n and replacement variable as \r\n.

Then I use wordlist = wordlist.replaceAll(separator, replacement); to replace all the characters, but when I display the wordlist again, it gives me the following result

onerntwornthree

I also tried splitting the wordlist by the substring separator into an array and then joining it again word by word into a new string separated by the replacement, but then it just gave me a result as

one\r\ntwo\r\nthree

Does anybody know how to solve this problem? In case you need it, here's the whole code:

System.out.print("Separator to replace: ");
separator = scanner.next( );

System.out.print("Replacement for separator: ");
replacement = scanner.next( );

wordlist = wordlist.replaceAll(separator, replacement);

I explained the whole idea, but if it is relevant, then I edited the post. — danrodi
– danrodi, Commented Jul 14, 2014 at 12:20
wordlist.replaceAll("\t", "\r\n") seems to work just fine: ideone.com/sdk1Dt — Keppil
– Keppil, Commented Jul 14, 2014 at 12:21
@danrodi: you query explicitly for the separator. And then strings are interpreted unescaped... — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Jul 14, 2014 at 12:29

Ninad Pingale · Accepted Answer · 2014-07-14 12:21:46Z

3

Your input character for tab seems to be incorrect.

This code gives

    String wordlist="one    two three";
    wordlist = wordlist.replaceAll("\t", "\r\n");
    System.out.println(wordlist);

This output-

one
two
three

answered Jul 14, 2014 at 12:21

Ninad Pingale

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1 Comment

Bex Over a year ago

This is not portable, though.

Bex · Accepted Answer · 2014-07-14 12:32:58Z

0

What you want to do is probably to split the string and the write the different lines one at a time to a PrintStream. That way you can use println.

Java is a platform independent language, and new lines are platform dependent. Making use of PrintStream.println will make sure your code is portable.

answered Jul 14, 2014 at 12:32

Bex

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Comments

willeM_ Van Onsem · Accepted Answer · 2014-07-14 12:35:17Z

0

Why do you set the separator to \n?, it should be \t I assume?

The following code works fine for jdoodle:

String s = "one\ttwo\tthree";
s = s.replaceAll("\t","\r\n");
System.out.println(s);

EDIT

The reason why this doesn't work is because you query the user for the separator and when he enters \t, this is a string with the first character \ and the second t and not an escape character.

You should use StringEscapeUtils.unescapeJava first.

Thus:

Scanner sc = new Scanner(System.in);
String separator = sc.nextLine();
separator = StringEscapeUtils.unescapeJava(separator);
String s = "one\ttwo\tthree";
s = s.replaceAll(separator,"\r\n");
System.out.println(s);

If org.apache.commons.lang.StringEscapeUtils is not available, you can do this explicitly:

Scanner sc = new Scanner(System.in);
String separator = sc.nextLine();
separator = separator.replaceAll("\\t","\t");
String s = "one\ttwo\tthree";
s = s.replaceAll(separator,"\r\n");
System.out.println(s);

demo

edited Jul 14, 2014 at 12:35

answered Jul 14, 2014 at 12:21

willeM_ Van Onsem

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5 Comments

danrodi Over a year ago

I tried the second option without the StringEscapeUtils, but it still keeps giving me the same result. Note that the replacement is also asked from the user and the separator doesn't have to be \t necessarily, it could also be \n.

willeM_ Van Onsem Over a year ago

Well, how do you enter the replacement? With tabs or with (explicit) "\t"?

danrodi Over a year ago

If using the example I explained my problem with, when asked for separator I type in \t and press Enter, then I'm asked for replacement where I type in \r\n and press Enter again.

willeM_ Van Onsem Over a year ago

You need to perform two StringEscapeUtils.unescapeJava (on both separator and replacement)...

danrodi Over a year ago

Used separator = separator.replaceAll("\\t","\t"); and replacement = replacement.replaceAll("\\r\n","\r\n");, still the same.

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